Telephone subscribers can own their own equipment and connect such equipment to the incoming telephone line of a telephone service provider at a device typically connected to the side of the subscriber's dwelling or place of business, hereinafter referred to as the "subscriber building." Thus, the device provides a "demarcation point" that is the connection point between the equipment that is accessible to the subscriber (the "subscriber equipment") and equipment that is accessible only to the service provider (the "service provider equipment"). The demarcation point is helpful in fault detection and isolation by easily allowing for the determination of whether a fault exists in the service provider equipment or the subscriber equipment.
Typically, the demarcation point is provided by a telephone network interface device (NID). A conventional NID is housed within a cabinet, typically called a building entrance terminal (BET), having both a service provider compartment and a subscriber compartment for mounting the service provider and subscriber equipment, respectively. These separate compartments are accessible through separate doors or covers. This permits the subscriber to have access to the subscriber equipment to allow the subscriber to test the telephone line at the demarcation point. However, the subscriber does not have access to the service provider compartment.
Typically, NIDs provide a telephone jack for connection to the incoming telephone line from the service provider and a telephone plug for connection to the subscriber telephone line. When the plug is inserted into the jack, a telephone connected to the subscriber telephone line is rendered operable. If the telephone becomes inoperable, the telephone plug can be unplugged from the telephone jack, thus providing a demarcation point to permit the plug of an operating telephone to be plugged into the jack to facilitate the determination of whether the fault exists in the service provider equipment or in the subscriber equipment.
Conventional NIDs are generally box-shaped units that are mounted to the vertical outside surface of the subscriber building. Conventional NIDs have a base surface in the subscriber compartment onto which various equipment is connected. Such equipment includes a line module, which houses the jack into which the plug is inserted to connect the subscriber line to the incoming telephone company line. The line module typically has a bottom, which is connected to the base surface in the subscriber compartment of the NID. In conventional NIDs, the base surface in the subscriber compartment is located above the "bottom" of the NID, i.e., the portion of the NID that contacts the subscriber building. Thus, conventional NIDs do not utilize the space between the base surface and the bottom of the NID.